The industrial processes for production of commodity chemicals and specialty chemicals often use transition metal catalyzed reactions, which are performed in organic solvents. However in recent years, these organic solvents are under close scrutiny with regard to the increasing environmental regulatory restrictions because of their intrinsic toxicity as well as the safety hazard due to their flammable nature. The use of water is a solution to these problems. However, water is not a friendly solvent for most transition metal catalysts because of their solubility in water as well as their sensitivity to water. Accordingly, the use of supercritical fluids, especially supercritical carbon dioxide provides an attractive solution.
It has been shown that supercritical fluids are useful as media for extraction and chromatography in academic laboratories as well as industrial processes P. G. Jessop, T. Ikariya, and R. Noyori, Science, 269, 1065-1069 (1995)!. Supercritical fluids also provide advantages as unique reaction media, e.g., the density, polarity, viscosity, diffusivity, and solvating ability of supercritical fluids can be dramatically changed by small variation of the pressure and/or temperature. L. Boock, B. Wu, C. LaMarca, M. Klein, and S. Paspek, CHEMTECH, 719-723 (1992); G. Kaupp, Angew. Chem. Int. Ed. Engl., 33, 1452-1455 (1994)!. It has recently been demonstrated that increase in reaction rate and change in selectivity can be achieved by replacing conventional organic solvents by supercritical fluids such as supercritical carbon dioxide (scCO.sub.2) and supercritical water (scH.sub.2 O). P. G. Jessop, T. Ikariya, and R. Noyori, Science, 269, 1065-1069 (1995); J. A. Banister, P. D. Lee, and M. Poliakoff, Organometallics, 14, 3876-3885 (1995); S. Kainz, D. Koch, W. Baumann, and W. Leitner, Angew. Chem., Int. Ed. Engl., 36, 1628-1630 (1997); J. W. Rathke, R. J. Klingler, and T. R. Krause, Organometallics, 11, 585 (1992)!.
As a medium for organic synthetic reactions and homogeneous catalysis, scCO.sub.2 appears to be most suitable because of its mild critical point, i.e., T.sub.c =31.degree. C., P.sub.c =72.9 atm. In fact, free radical reaction, polymerization, hydrogenation, hydroformylation, and carboxylation reactions have been successfully carried out in scCO.sub.2.S. Kainz, D. Koch, W. Baumann, and W. Leitner, Angew. Chem., Int. Ed. Engl., 36, 1628-1630 (1997); J. W. Rathke, R. J. Klingler, and T. R. Krause, Organometallics, 11, 585 (1992); Y. Guo, and A. Akgerman, Ind. Eng. Chem. Res., 36, 4581-4585 (1997); P. G. Jessop, Y. Hsiao, T. Ikariya, and R. Noyori, J. Am. Chem. Soc., 118, 344-355 (1996); P. G. Jessop, T. Ikariya, and R. Noyori, Organometallics, 14, 1510-1513 (1995); P. G. Jessop, Y. Hsiao, T. Ikariya, and R. Noyori, J. Chem. Soc., Chem. Commun., 707-708 (1995); P. G. Jessop, Y. Hsiao, T. Ikariya, and R. Noyori, J. Am. Chem. Soc., 116, 8851-8852 (1994); P. G. Jessop, T. Ikariya, and R. Noyori, Nature, 368, 231-233 (1994); J. W. Rathke, and R. J. Klingler, U.S. Pat. No. 5,198,589 (1993); J. W. Rathke, R. J. Klingler, and T. R. Krause, Organometallics, 10, 1350-1355 (1991); M. T. Reetz, W. Konen, and T. Strack, Chimia, 47, 493 (1993); J. M. DeSimone, E. E. Maury, Y. Z. Menceloglu, J. B. McClain, T. J. Romack, and J. R. Combes, Science, 265, 356-359 (1994); J. M. DeSimone, Z. Guan, and C. S. Elsbernd, Science, 257, 945-947 (1992); M. J. Burk, S. Feng, M. F. Gross, and W. Tumas, J. Am. Chem. Soc., 117, 8277-8278 (1995)!.
It is anticipated that increased reaction rate and selectivity may result from the following characteristics of scCO.sub.2 in homogeneous catalysis: (i) local clustering of reactants and a very large activation volume near the critical point, (ii) weakened solvation around reactive species, (iii) rapid diffusion of solute molecules, (iv) high solubility of gases, (v) disfavoring the cage effects in radical processes.P. G. Jessop, T. Ikariya, and R. Noyori, Science, 269, 1065-1069 (1995)! In addition to these characteristics, scCO.sub.2 serves as environmentally benign, non-flammable reaction medium that does not cause solvent residues and waste originated from conventional organic solvents. The separation of the product(s), catalyst, and reactant(s) can be easily performed through selective precipitation.P. G. Jessop, T. Ikariya, and R. Noyori, Science, 269, 1065-1069 (1995)!.
In spite of the recent recognition of these very useful features of scCO.sub.2, only a very limited number of homogeneous catalytic reactions have been investigated using scCO.sub.2 as the medium.P. G. Jessop, T. Ikariya, and R. Noyori, Science, 269, 1065-1069 (1995); J. W. Rathke, R. J. Klingler, and T. R. Krause, Organometallics, 10, 1350-1355 (1991); M. T. Reetz, W. Konen, and T. Strack, Chimia, 47, 493 (1993); M. J. Burk, S. Feng, M. F. Gross, and W. Tumas, J. Am. Chem. Soc, 117, 8277-8278 (1995)!.
Hydroformylation of propene catalyzed by Co.sub.2 (CO).sub.8 in scCO.sub.2 has been studied J. W. Rathke, R. J. Klingler, and T. R. Krause, Organometallics, 10, 1350-1355 (1991); Y. Guo, and A. Akgerman, Ind. Eng. Chem. Res., 36, 4581-4585 (1997)!. Hydroformylation of olefins catalyzed by Group VIII metal catalysts, which may be complexed with phosphine ligands, in scCO.sub.2 have been patented J. W. Rathke and R. J. Klingler, U.S. Pat. No. 5,198,589 (1993)!. Hydroformylation of alkenes catalyzed by HMn(CO).sub.5 was also studied P. G. Jessop, T. Ikariya, and R. Noyori, Organometallics, 14, 1510-1513 (1995)!. Hydroformylation of 1-octene catalyzed by a rhodium complex with tris(m-perfluoroalkyl-substituted phenyl)phosphine, which results in a catalyst that is substantially more soluble in supercritical carbon dioxide than those using conventional non-fluorinated phosphine ligands. was reported S. Kainz, D. Koch, W. Baumann, and W. Leitner, Angew. Chem., Int. Ed. Engl., 36, 1628-1630 (1997)!.
The cobalt-catalyzed processes need high pressure and high temperature in a manner similar to the conventional cobalt-catalyzed hydroformylation process in organic solvents. The manganese-catalyzed process is not practical in terms of efficacy. The rhodium-catalyzed process using tris(m-perfluoroalkyl-substituted phenyl)phosphine has been carried out at 220 atm total pressure and the pressure of hydrogen and carbon monoxide (1:1) at ambient temperature is 60 atm, which are still quite high pressures.
One of the objects of the present invention is to provide carbonylation reaction processes including hydroformylation and cyclohydrocarbonylation of functionalized and unfunctionalized alkenes, alkadienes, and alkynes catalyzed by Group VIII transition metal complexes in scCO.sub.2 that are different from and/or improved over the prior art. Another object is to provide such processes that can be carried out at lower pressures than the prior art. Another object is to provide such processes that employ a ligand that does not need a special modification such as introducing perfluoroalkyl group(s) to provide adequate solubility of the catalyst in supercritical carbon dioxide. Applicants have discovered that these objects can be achieved by using a phosphite ligand in combination with a Group VIII transition metal catalyst or catalyst precursor.